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OpenEBS Control Plane Chaos Experiment Details

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Experiment Metadata

Type	Description	Tested K8s Platform
OpenEBS	Kill the OpenEBS control plane pods and check if they are rescheduled and healthy	GKE, EKS

Prerequisites

• Ensure that the Litmus Chaos Operator is running by executing kubectl get pods in operator namespace (typically, litmus). If not, install from here

• Ensure that the openebs-control-plane-chaos experiment resource is available in the cluster by executing kubectl get chaosexperiments in the openebs namespace. If not, install from here

Entry Criteria

• OpenEBS control plane pods are healthy before chaos injection

Exit Criteria

• OpenEBS control plane pods are healthy after chaos injection

Details

• This scenario validates graceful & forced terminations of OpenEBS control plane pods
• List of control plane components killed in this experiment:
  • maya-apiserver
  • openebs-admission-server
  • openebs-localpv-provisioner
  • openebs-ndm-operator
  • openebs-provisioner
  • openebs-snapshot-operator
  • openebs-ndm

Integrations

• Pod kill is achieved using either the litmus or powerfulseal chaos libraries.
• The desired lib can be configured using the env variable LIB using litmus or powerfulseal.

Steps to Execute the Chaos Experiment

• This Chaos Experiment can be triggered by creating a ChaosEngine resource on the cluster. To understand the values to be provided in a ChaosEngine specification, refer Getting Started

• Follow the steps in the sections below to create the chaosServiceAccount, prepare the ChaosEngine & execute the experiment.

Prepare chaosServiceAccount

Use this sample RBAC manifest to create a chaosServiceAccount in the desired (openebs) namespace. This example consists of the minimum necessary role permissions to execute the experiment.

Sample Rbac Manifest

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: control-plane-sa
  namespace: openebs
  labels:
    name: control-plane-sa
    app.kubernetes.io/part-of: litmus
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: control-plane-sa
  namespace: openebs
  labels:
    name: control-plane-sa
    app.kubernetes.io/part-of: litmus
rules:
- apiGroups: ["","litmuschaos.io","batch","apps"]
  resources: ["pods","deployments","pods/log","events","jobs","configmaps","chaosengines","chaosexperiments","chaosresults"]
  verbs: ["create","list","get","patch","update","delete"]
- apiGroups: [""]
  resources: ["nodes"]
  verbs: ["get","list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: control-plane-sa
  namespace: openebs
  labels:
    name: control-plane-sa
    app.kubernetes.io/part-of: litmus
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: control-plane-sa
subjects:
- kind: ServiceAccount
  name: control-plane-sa
  namespace: openebs

Prepare ChaosEngine

• Provide the application info in spec.appinfo
• Override the experiment tunables if desired in experiments.spec.components.env
• To understand the values to provided in a ChaosEngine specification, refer ChaosEngine Concepts

Supported Experiment Tunables

Variables	Description	Specify In ChaosEngine	Notes
LIB	The chaos library used to inject the chaos	Optional	Defaults to `litmus`. Supported: `litmus, powerfulseal`
INSTANCE_ID	A user-defined string that holds metadata/info about current run/instance of chaos. Ex: 04-05-2020-9-00. This string is appended as suffix in the chaosresult CR name.	Optional	Ensure that the overall length of the chaosresult CR is still < 64 characters

Sample ChaosEngine Manifest

apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: control-plane-chaos
  namespace: openebs
spec:
  # It can be active/stop
  engineState: 'active'
  appinfo:
    appns: 'openebs'
    applabel: 'name=maya-apiserver'
    appkind: 'deployment'
  chaosServiceAccount: control-plane-sa
  experiments:
    - name: openebs-control-plane-chaos
      spec:
        components:
          env:
            - name: FORCE
              value: ''

Create the ChaosEngine Resource

• Create the ChaosEngine manifest prepared in the previous step to trigger the Chaos.

  kubectl apply -f chaosengine.yml -n openebs

• If the chaos experiment is not executed, refer to the troubleshooting section to identify the root cause and fix the issues.

Watch Chaos progress

• View pod terminations by setting up a watch on the pods in the OpenEBS namespace

  watch -n 1 kubectl get pods -n openebs

Check Chaos Experiment Result

• Check whether the OpenEBS control plane is resilient to the pod failure, once the experiment (job) is completed. The ChaosResult resource naming convention is: <ChaosEngine-Name>-<ChaosExperiment-Name>.

  kubectl describe chaosresult control-plane-chaos-openebs-control-plane-chaos -n openebs

Recovery

• If the verdict of the ChaosResult is Fail, and/or the OpenEBS components do not return to healthy state post the chaos experiment, then please refer the OpenEBS troubleshooting guide for more info on how to recover the same.

OpenEBS Control Plane Chaos Demo [TODO]

• A sample recording of this experiment execution is provided here.